The present invention relates to a vacuum-cleaner tube. More particularly this invention concerns a latch for a telescoping vacuum-cleaner tube.
A standard telescoping tube wand for a vacuum cleaner typically as described in German 199 24 451 or copending U.S. patent application Ser. No. 09/578,600 filed May 25, 2000 now U.S. Pat. No. 6,431,607 has an outer tube, an inner tube telescopingly received in the outer tube and provided with an axially extending row of detent recesses, and a latch on the outer tube for relatively axially fixing the inner and outer tubes. The latch has a sleeve surrounding the inner tube, a housing on the sleeve opening toward the row, a locking body in the housing displaceable into and out of engagement with a selected one of the detent recesses, an actuator rotatably mounted in the housing and bearing directly upon the body for locking the body in the selected one of the recesses in a locking position of the actuator and enabling movement of the body out of the selected one of the recesses in an unlocked position of the actuator, and a spring acting upon the actuator and biasing the actuator into the locking position.
With this system, even upon the development of high axial forces and the possible application of substantial outward radial force to the locking body in the locked position, this position will be maintained since there is no force which will tend to rotate the actuator. There is no spring or the like between the rotatable actuator and the locking body and thus the locking body is mechanically fixed in its locked position without any yieldability until the rotatable actuator is displaced. The spring acting on the rotatable member merely serves to bias the latter into the locking position and does not itself absorb any of the locking force or yield to any radial force which can result from the application of large axial forces to the inner and outer tubes.
This structure is fairly complicated. It is difficult to assemble and, due to its many parts, can come apart and fail in use.
It is therefore an object of the present invention to provide an improved latch system for a telescoping vacuum-cleaner wand.
Another object is the provision of such an improved latch system for a telescoping vacuum-cleaner wand which overcomes the above-given disadvantages, that is which is of simple and rugged construction.
A vacuum-cleaner wand has according to the invention an inner tube extending along an axis and formed with an axially extending row of radially outwardly open recesses, an outer tube engaged coaxially around the inner tube, and a latch base part fixed to the outer tube and formed with an elastically deformable web carrying a latching block displaceable radially between an inner position engageable radially in the recesses and an outer position unengageable in the recesses. The base part also is formed with a pair of radially outwardly projecting guide walls forming radially inwardly directed guide edges. A movable latch part fitting over the base part is formed with a pair of radially inwardly projecting guide walls forming radially outwardly directed guide edges sliding on the guide edges of the base part so that the movable part can slide on the base part between axially offset latched and unlatched positions. A radially inwardly projecting actuating bump formed in the movable part bears in the latched position radially inward on the block and holds the block in the inner position and is axially offset from the block in the unlatched position.
According to the invention the walls and guide edges extend axially. Thus the movable part slides axially between its positions. The edges are of barb section and the walls have outer faces extending generally radially. Furthermore the walls of the movable part engage between the walls of the base part and the base part is formed with transverse end walls extending between and bridging ends of the base-part guide walls. This structure ensures accurate guiding with a very robust connection that will have a long service life.
The movable part in accordance with the invention is generally cup shaped and fits over the base part. In addition the movable-part guide walls project from an inner surface of the movable part and the block is unitarily formed with the movable part. The actuating block is between the movable-part guide walls and the outer part forms a space into which the block can move when in the outer position.
The parts according to the invention are formed with respective abutments engaging axially against each other in the unlatched position. Furthermore a spring is braced axially between the parts and urges the movable part into the latched position. This spring is a compression spring and one of the parts is formed with a pin over which the spring is engaged and the other of the parts has an abutment against which the spring bears. Alternately the spring is U-shaped, lies generally in a plane perpendicular to the axis, has outer ends seated in the outer tube, and a bight portion coupled to the movable part. In another arrangement according to the invention a center abutment is fixed on the outer tube between a pair of springs axially oppositely engaging the center abutment. Respective end abutments formed on the movable part engage the springs to urge the movable part into the latched position. Thus the movable part is displaceable axially oppositely from the latched position into a pair of unlatched positions. Any axial movement of the outer part, in either direction, will unlatch the inner tube and allow the wand to be lengthened or shortened.
Formations on the tubes preventing relative rotation of the tubes about the axis. These formations include a radially projecting and axially extending ridge on one of the tubes and a radially open and axially extending groove on the other of the tubes. The ridge is on the base part and the groove is in the inner tube.